RYNO To Heinlein - Your Tumblebug Is Ready!

The RYNO is a fully electric monocycle, a one-wheeled scooter you can buy today.

(RYNO video)

...the RYNO balances itself front-to-back when standing still. With both feet on the ground, it nudged around to keep my center of gravity poised directly over the axle. With only one wheel, side-to-side balance is up to you. It's a big wheel, though, wearing a 240-millimeter-wide motorcycle tire usually found on big ol' Harley-Davidsons. There's a brake lever on the right, though it doesn't work the way you'd expect it to (more on that in a minute). Turning the handlebars swivels the seat on a pivot somewhere behind your tailbone, which feels completely foreign when standing still. And that's it for controls—your body position does the rest.

After about 5 minutes, the whole process began to feel natural. Icy, frigid conditions prevented me from taking an extended ride, but Chris says most folks get the basics after about 15 minutes, with master maneuvering taking just a few days.

Once your brain adapts, the RYNO is astoundingly surefooted (and man, I never expected to say that about a unicycle). Credit the construction, which mounts the dual motors and controllers, three gyroscopes, two removable batteries, and all the accompanying computer brains inside the hub of the 18-inch wheel. With a center of mass somewhere between your shins and software that reacts instantaneously to your every lean, the RYNO feels nearly un-toppleable.

Fans of Robert Heinein's 1940 classic The Roads Must Roll recall the tumblebug:

Gaines and Harvey mounted tumblebugs, and kept abreast of the Cadet Captain, some twenty-five yards behind the leading wave. It had been a long time since the Chief Engineer had ridden one of these silly-looking little vehicles, and he felt awkward. A tumblebug does not give a man dignity, since it is about the size and shape of a kitchen stool, gyro-stabilized on a single wheel.
(Read more about Robert Heinlein's Tumblebug.)

Here's the artist's view of what a tumblebug looked like, from the cover of Astounding Science Fiction: